Learn These Terms Before Lampworking

Remember the last time you learned a new hobby? You loved reading all the books and magazine articles, but the jargon left you a bit confused. Lampworking is no exception, but grasping the lingo is not hard at all. Here’s a detailed list of common terms. Once you understand all these terms, you’ll be an expert!


Annealing is the uniform and controlled cooling of a finished piece of glass.  Without proper annealing the finished work may eventually crack or break.

Annealing Temperature Range is the temperature at which molecular stresses are relieved in the cooling process after heating the glass.

Bead Separator (also known as bead release) is a thick liquid that is applied to a mandrel to keep the hot glass from sticking to the stainless steel.  A simple bead release is a mixture of alumina and high-fire clay with water.

Borosilicate Glass (also known as Hard Glass) is a glass composed of boron and silica.  An example would be Pyrex, a brand name of this type of glass.

Cane is a thin rod of pulled or twisted glass.

Cased Beads or Encased Beads are composed of two or more fused layers of glass.  The final or outside layer of glass is usually clear or transparent.

Coefficient of Thermal Expansion or COE is the linear measure of how much a material elongates within a given temperature change.

Borosilicate – 33 COE
Bullseye – 90 COE
Uroboros – 96 COE
Spectrum – 96 COE
Lauscha – 104 COE
CiM – 96-104COE
Effetre – 104 COE
Vetrofond – 104 COE
Satake – 125 COE

Cold-working is mechanically altering the appearance of glass when it is cold.  Grinding, etching, cutting and faceting are examples of cold-working techniques.

Compatibility refers to types of glass which have the same coefficient of expansion – COE.  When glass is heated it expands and when it is cooled it contracts.  The ability to contract at the same rate is essential.  When glass is incompatible breakage will usually occur.

Controller controls the cooling, heating and maintaining of the temperature of a kiln.

Devitrification occurs on the surface of some glass when crystals form due to the loss of the fluxing agent when over heated. The glass often takes on a matte or dull finish. Certain types and colors of glass are more susceptible to this than others, one particular shade of Moretti purple in particular, which is often referred to by beadmakers as “Evil Devitrifying Purple”, or, EDP.

Dichroic Glass appears one color in reflected light and the complementary color in transmitted light.  The iridescent appearance is caused by a thick layer of metallic oxides. (di = two; chroic, chrome = color).

Drawn Beads are cut from a hollow pulled tube.  The process usually refers to furnace glass.  

Didymium Lenses are used by lampworkers to protect the eye from infrared and ultraviolet radiation from hot glass and to eliminate the yellow sodium flare created when glass is worked in the flame.

Etching is a surface finish that results in a matte or frosted appearance.  Hydrofluoric acid, sandblasting and tumbling are all methods used for etching.

Fiber Blanket is a thick insulating blanket made from non-asbestos fibers.  Some beads may be prevented from thermal shock by placing them between two layers of fiber blanket so that they can be annealed at a later time.

Filagrana is a rod with a solid color core cased in a clear or transparent color.

Fire Polish is to create a glassy finish on glass by the use of heat.

Flame Annealing is a method of slowly cooling a bead in the outer reaches of the flame of the torch.

Flameworking is the manipulation of glass by means of a torch.

Frit is crushed glass of varying mesh sizes.

Fuming is the process of melting or burning a metal or metallic salt onto the surface of a piece of glass.  The metal, often gold or silver, is heated within a flame until it vaporizes.  The vapor is then deposited onto the surface of the glass creating an iridescent glow.  Metallic vapors can be toxic.  Safety precautions should be taken when fuming.

Furnace-worked Beads are beads that have been made with the use of a pot furnace and glory hole.  Traditional glassblowing techniques are often utilized in the production of these beads. Also known as Drawn Beads.

Gather is a glob of glass on the end of a punty or blowpipe. In lampworking the gather is formed by melting the end or a rod and allowing more of the rod to be fed into the flame so that the molten area of the glass is increased.

Glass is a non-crystalline material with the mechanical rigidity of a solid and the atomic qualities of a liquid. Most glass is composed of silica, sodium oxide and a stabilizer such as calcium oxide.

Glass Enamels are powdered glass applied to and bonded by heat to a heat resistant surface such as glass, fine silver, copper or pure gold.

Kiln (also known as oven) is a heated chamber used for the fusing, slumping, casting, or annealing of glass. Kilns are typically powered with electricity.

Mandrel is a stainless steel rod used in beadmaking.

Maria  Flattened disk made on the end of glass rod, or punty, to provide a wider surface for attaching a glass bundle.

Marver is a surface, often metal, stone or graphite, on which hot glass is rolled to smooth or shape.

Millefiori are a specific type of murrine which resemble a flower. Translated from the Italian it literally means a thousand flowers. Millefiori are slices of a mosaic cane that have been built up from concentric layers of glass.

Mold is a form which is used to shape glass. Typically molds for lampworking are made from metal, wood or graphite. For kiln forming the molds are constructed from heat tolerant fiber paper or a plaster-like investment.

Murrina (singular) is a slice of cane that has been made by composing different colors of glass to create an image. The design will run the full length of the cane. Murrine (plural) can be made using various hot and cold techniques. The end result can depict faces, animals, numbers, letters and other non-linear images.

Oxidizing Flame is a flame that has an excess of oxygen, causing the flame to be hotter, which could boil the glass.

Punty is a metal or glass rod used to handle molten glass.

Raking, Feathering, Trailing are all decorative techniques of drawing softened threads of glass over the surface of a hot piece of glass. Graphite or metal tools may be used to push and pull the threads of color to their desired position.

Reducing Flame is a flame which is deficient in oxygen. Using a reducing flame can steal oxygen from metal oxide colorants in the glass making it dull.

Strain Point is the temperature below which, stress can neither be added nor subtracted from the glass. Below this temperature, the molecules of the glass are “frozen” in place.

Stringers are thin spaghetti-like pieces of glass. They are often used for surface decoration or in creating small details of design.

Surface-Mix Torch is a torch that is constructed so that the gasses are mixed at the surface of the torch.

Thermal Conductivity is a measure of how quickly heat moves through a material.

Thermal Expansion is the property of a material that when it is heated it’s dimensions increase or expand.

Thermal Shock is the strain created by abruptly heating and cooling a piece of glass. Glass can be thermal shocked when it is heated or cooled too fast and breakage will occur.

Torch is a heat source used for lampworking. A mixture of compressed oxygen and fuel gas (such as propane, natural or MAPP) is burned.

Tumbling is the technique of abrading the surface of glass using an electronic tumbling machine and various metal or plastic media and chemical compounds.

Twistie is a rod or stringer made by twisting two or more colors of glass together.

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About LeahBeads 21 Articles
Leah has been working with all types of glass since 2000. She loves sharing her knowledge and helping people experience the thrill of glass beadmaking. She also runs and competes in triathlons when she's not at the torch.

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